When a pipe is to be joined to a fitting having an internal shoulder it is common for the free end of the pipe to be inserted into the fitting to an extent sufficient to enable the end of the pipe to abut the shoulder. The pipe and fitting should not be welded together in such relative positions, however, because of the likelihood that the weld, the pipe, or the fitting will crack or break due to thermal expansion and contraction of the pipe and fitting. Accordingly, it is the practice to provide a clearance between the free end of the pipe and the shoulder of the fitting, such clearance amounting to at least one sixteenth inch according to most welding standards. Various tools and apparatus have been proposed heretofore to ensure that such clearance is provided prior to the commencement of the welding operation. For example, a tool of the kind disclosed in applications Ser. Nos. 77,859, filed Sept. 21, 1979, now U.S. Pat. No. 4,306,345 and 148,416, filed May 9, 1980, now U.S. Pat. No. 4,378,937 and the patents, publications, and other devices referred to in such applications. Although such tools are well suited for their intended purposes, it is not possible for an inspector of a string of welded pipes and fittings to ascertain from inspection whether the required clearance has in every case been provided between the shoulder of a fitting and the adjacent end of a length of pipe. An object of this invention, therefore, is to provide a tool for use in welding pipes and fittings together and which is equipped with means for providing visual confirmation that a clearance between a fitting's internal shoulder and the adjacent end of a length of the pipe has been provided.
Tools of the kind referred earlier usually are hand-held and maintained in clamping relation on a pipe during tack welding of the fitting to the pipe. In some cases the tool interferes to some extent with the tack welding operation. Another object of the present invention, therefore, is to provide for relative movement between the tool and the pipe while the tool is in its clamping position so as to minimize interference with the tack welding operation.